Abstract Summary: Eastern Europe and Central Asia (EECA) is the only region where HIV incidence and mortality has increased, primarily fueled by people who inject drugs (PWID) who interface regularly with prisons. In Kyrgyzstan?s (KYR) prisons, HIV prevalence among opioid injectors exceeds 30%, and within prison drug injection is associated with being HIV+. KYR presents a unique opportunity to develop an HIV prevention program for prison settings because all the 15 HIV prevention programs recommended for prisons are available there. Based on many commonalities shared by prisons globally, lessons learned in the KYR prisons can inform HIV prevention efforts in other countries, including the US that is experiencing an explosive opioid epidemic. Data suggests that prisoners who inject drugs may join addiction treatment programs, and influenced by peers. Harnessing these peer influences on prisoners to incorporate more effective use of formal healthcare services, especially of addiction treatment programs and syringe exchange within prison, is a WHO priority. Compared to professional outreach workers, peer-driven interventions (PDIs) are more efficient and cost-effective in recruiting and engaging PWID in HIV prevention, yet aside from scant peer education prison programs, PDIs have not involved prisoners or directly focused on reducing HIV risk through promoting engagement with addiction treatment or syringe exchange. To address these critical gaps, the mentored K01 Award will provide the candidate with training and mentoring, including a real-world two-arm study that focuses on primary HIV prevention among PWID in prisons. The first arm of the study (Project 1.1) develops, pilots, and assesses the feasibility of a 12-week in-prison PDI to reduce HIV risk among prisoners who inject drugs by increasing uptake of available prison addiction treatment programs. The study?s second arm (Project 1.2) uses ethnographic observation of the 12- week PDI, and qualitative interviews with study participants and prison staff after the PDI in both Experiment and Control prisons, to explore why the PDI is successful (or not), refine the PDI manual, and develop hypotheses attributing changes in outcomes to the PDI that will be tested within a future R01 to conduct a RCT. The candidate, Dr. Rozanova, is well-positioned to perform this work because of her strong medical sociology and qualitative skills that will be extended by further training in mixed-methods and biostatistics, and her commitment to more advanced training in HIV, addiction, and prison health after transitioning her career to the new field 2 years ago. Over 5 years, she will achieve her career goals to: 1) Gain experience in PDI development and implementation to address stigma-specific barriers to HIV prevention services in prison; 2) Master using ethnography and qualitative interviews combined with new quantitative skills to evaluate the success of an experiment from its stakeholders? perspective, and ultimately 3) develop an independent career path in patient-oriented research focused on HIV prevention, prison and global health, and addiction treatment. She will achieve her goals from an interdisciplinary team of mentors with expertise in HIV, addiction, prison health, experiments in criminal justice settings, and biostatistics and epidemiology, and through completion of relevant didactic work and seminars and conduct related research to apply the skills needed to become an independent researcher within the rich intellectual environment available at Yale University.